Biomimetic Microadhesion Guided Instant Spinning.

Animals create high-performance fibers at natural ambient conditions via a unique spinning process. In contrast, the spinning technologies developed by human beings are usually clumsy and require sophisticated skills. Here, inspired by adhesion-based silkworm spinning, we report a microadhesion guided (MAG) spinning technology for instant and on-demand fabrication of micro/nanofibers. Enabled by the adhesion between the spinning fluids and the microneedles, the MAG spinning can generate micro/nanofibers with programmable morphology. By further mimicking the head movement of the silkworm spinning, the MAG technology is extended with three different modes: straight, vibratory, and twisted spinning, which generate oriented fibers, hierarchical cross-linked fibers, and all-in-one fibers, respectively. Due to the prevalence of microadhesion and its unprecedented flexibility in operation, equipment-free MAG spinning is finally realized for instant fiber fabrication by only polymeric foams. Finally, the MAG spinning is demonstrated as a promising instant technology for emergent applications, such as wound dressing.

Electrospun polylactic acid nanofiber film modified by silver oxide deposited on hemp fibers for antibacterial fruit packaging.

Bacterial and fungal contamination have become major factors in fruit spoilage and damage, posing a potential risk to human health. In this work, polylactic acid (PLA) nanofibers combined with Ag2O-hemp fibers for a good antimicrobial effect were developed and applied to antimicrobial fruit fresh-keeping packages. The results of molecular simulation calculations showed that the strength of hydrogen bonds between Ag2O and hemp fibers reached 45.522 kJ·mol-1, which proved that Ag2O and with hemp fibers formed a stable deposition. The Ag2O-hemp fibers modified electrospun polylactic acid nanofibrous composite film exhibited favorable mechanical properties. The tensile strength reached 5.23 ± 0.05 MPa and the elongation at break reached 105.56 ± 3.95 %. The obtained nanofibrous composite film has good antibacterial activity against E. coli, S. aureus, A. niger, and Penicillium, which indicated that they could effectively inhibit the growth of bacteria and fungi. The cell experiments proved that the nanofibrous composite film had good biocompatibility with a cell survival rate of 100 %. The experimental results on the fresh-keeping of red grapes showed that the PLA nanofibrous composite film modified by the Ag2O-hemp fibers could effectively prolong the spoilage time of red grapes at room temperature. Compared with the blank group, the freshness period of PLA nanofiber film modified by Ag2O-hemp fibers could be extended for more than 5 days. The hardness of 15 days (1.94 ± 0.19 × 105 Pa) was basically the same as that of 1 day (2.05 ± 0.06 × 105 Pa). The results were superior to commercially available PE preservation films. The above research results indicated that the Ag2O-hemp fibers modified PLA nanofibrous composite film had potential application prospects in the field of fruit fresh-keeping package.

"Sandwich-like" structure electrostatic spun micro/nanofiber polylactic acid-polyvinyl alcohol-polylactic acid film dressing with metformin hydrochloride and puerarin for enhanced diabetic wound healing.

A diabetic wound is a typical chronic wound with a long repair process and poor healing effects. It is an effective way to promote diabetic wound healing to design electrospinning nanofiber films with drug-assisted therapy, good air permeability and, a multilayer functional structure. In this paper, a diabetic wound dressing with a "sandwich-like" structure was designed. Metformin hydrochloride, loaded in the hydrophilic PVA inner layer, could effectively promote diabetic wound healing. The drug release was slowed down by osmosis. The laminate film dressing had good mechanical properties, with tensile strength and elongation at break reaching 5.91 MPa and 90.47 %, respectively, which was close to human skin. The laminate film loaded with erythromycin and puerarin in the hydrophobic PLA outer layer had good antibacterial properties. In addition, due to the high specific surface of the electrostatic spun film, it exhibited high water vapor permeability. It facilitates the gas exchange between the wound and the outside world. The cell experiments proved that the laminate film dressing had good biocompatibility. There was no toxic side effect on cell proliferation. In the diabetic animal wound model, it was shown that the closure rate of diabetic wound repair by laminate film reached 91.11 % in the second week. Our results suggest that the "sandwich-like" nanofiber film dressing could effectively promote the healing process and meet the various requirements of diabetic wound dressing as a promising candidate for future clinical application of chronic wound dressings.

Short implants versus longer implants in the posterior alveolar region after an observation period of at least five years: A systematic review and meta-analysis.

OBJECTIVES: This meta-analysis compared clinical outcomes, including survival rate, marginal bone loss (MBL), and technical and biological complications of short implants (<7 mm) and long implants (≥7 mm) placed in the posterior alveolar bone. SOURCES: Electronic (via PubMed, EMBASE, Cochrane Library) and manual searches were performed for articles published prior to November 29, 2019. STUDY SELECTION: The review protocol was registered with PROSPERO (CRD42019140718). Only randomized controlled trials (RCTs) comparing short implants and standard implants in the same study after an observation period of at least five years were included. DATA: Nine RCTs were included in this study. The survival rates of short implants (<7 mm) ranged from 86.7 %-98.5 %, whereas the survival rates of longer implants (≥7 mm) were 95.1%-100% with follow-up ranging from 5 to 10 years. Dichotomous variables were compared using the Mantel-Haenszel (MH) method, and continuous variables were compared using the inverse variance (IV) method. The random effects model and the fixed effects model were used. Meta-analyses showed that short implants had a poorer survival rate than longer implants (P = 0.008). Short implants were associated with lower MBL than longer implants (P < 0.001). The biological complications of short implants were lower (P < 0.001) and the technical complications were higher, than those of long implants (P = 0.006). CONCLUSIONS: The results indicate that although the survival rate of short implants in the maxilla may be lower than that of long implants, the survival rate of short implants in the mandible is similar to that of long implants, and short implants can result in a lower rate of biological complications. The conclusions should be interpreted with caution due to the limited numbers of participants and implants. CLINICAL SIGNIFICANCE: When selecting the length of implants, surgeons should consider survival rate, the location of implant placement, their own clinical experience, and the incidence of complications.

Fabrication, properties and applications of soy-protein-based materials: A review.

The environmental crisis caused by the use of petroleum-based nondegradable polymers and the impending petroleum finite resources have directly threatened human being's sustainable development. Therefore, ecofriendly polymers based on natural renewable resources are attracting more and more attention. As the byproducts of soy oil industries, soy protein, is regarded as a viable alternative for petroleum-based polymeric products. In order to improve the physical properties, especially the mechanical properties and water resistance that limit their extensive applications, different modifications were adopted. Among these efforts, incorporating nanoparticles and blending with other polymers are proved to be effective ways. The properties of the resulting materials are highly dependent on the processing methods, nature of the components, dispersion status and the compatibility. This review intends to provide a clear overview on preparation, properties, and applications of soy-protein-based materials. These biodegradable materials will find more and more potential applications in biodegradable foams, edible films, packaging materials, biomedical materials, etc.

Building Ion-Conduction Highways in Polymeric Electrolytes by Manipulating Protein Configuration.

Solid polymer electrolytes play a critical role in the development of safe, flexible, and all-solid-state energy storage devices. However, the low ion conductivity has been the primary challenge impeding them from practical applications. Here, we propose a new biotechnology to fabricate novel protein-ceramic hybrid nanofillers for simultaneously boosting the ionic conductivity, mechanical properties, and even adhesion properties of solid polymer electrolytes. This hybrid nanofiller is fabricated by coating ion-conductive soy proteins onto TiO2 nanoparticles via a controlled denaturation process in appropriate solvents and conditions. It is found that the chain configuration and protein/TiO2 interactions in the hybrid nanofiller play critical roles in improving not only the mechanical properties but also the ion conductivity, electrochemical stability, and adhesion properties. Particularly, the ion conductivity is improved by one magnitude from 5 × 10-6 to 6 × 10-5 S/cm at room temperature. To understand the possible mechanisms, we perform molecular simulation to study the chain configuration and protein/TiO2 interactions. Simulation results indicate that the denaturation environment and procedures can significantly change the protein configuration and the protein/TiO2 interactions, both of which are found to be critical for the ion conductivity and mechanical properties of the resultant solid composite electrolytes. This study indicates that biotechnology of manipulating protein configuration can bring novel and promising strategies to build unique ion channels for fast ion conduction in solid polymer electrolytes.